Sensors (e.g., thermocouples, strain gauges, and transducers) typically emit analog electronic signals that are subsequently converted to digital signals using an A/D converter. Unfortunately, analog electronic signals are susceptible to picking up electronic noise as they travel from the sensors to the A/D converter. Therefore, electronic circuits have been developed to minimize the amount of noise in these analog signals.
Typically, the electronic circuits that have been developed include a relatively large number of components. For example, some such circuits make use of two single-pole double-throw (SPDT) switches for every sensor that sends an input signal to an A/D converter. As such, when numerous sensors are electrically connected to the same A/D converter, the total number of switches that must be included in the circuit connecting the sensors and the A/D converter can become prohibitively large.
Among the disadvantages of including many components in a circuit between sensors and an A/D is that, with each additional component, the probability that at least one of the components will break down and cause a malfunction in the circuit increases. Also, additional components increase the size of the circuit and require the use of additional circuit board area, which may not be available if the circuit is included in a relatively small device.
At least in view of the above, it would be desirable to reduce the amount of signal noise that is generated between a plurality of sensors and an A/D converter using smaller, more reliable and more efficient circuitry than prior art circuit.